Flat mop



FIG. 1 is a top perspective view of a flat mop, showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof;

FIG. 8 is a bottom view thereof; and,

FIG. 9 is a perspective view thereof when it is being used.

The broken lines in the drawings illustrate the portions of the flat mop, which form no part of the claimed design. 

CLAIM The ornamental design for a flat mop, as shown and described. 